Variable-speed gear or torque converter



Feb. 3, 1931. c. ST.J. SPRIGG 1,791,336

VARIABLE SPEED 0R TORQUE CONVERTER Filed Feb. '7, 1930 2 Sheets-Sheet l 2 fT i/ 0 Feb. 3, 1931. c, $T J spm 1,791,386

VARIABLE SPEED GEAR OR TORQUE CONVERTER Filed Feb. 7, 1930 2 Sheets-$heet 2 0 i L2 L I;

C511 fi r jij Patented Feb. 3, 1931 S'EATES .CHRISTOPHER ST. JOHN SPRIGG, OF LONDON, ENGLAND VARIABLE-SPEED GEAR OR TORQUE CONVERTER Application filed February 7,'1930, Serial -NO.-426,660, and in Great Britain February 19, 1929.

This invention relates to variable speed gears or torque converters of the kind comprising driving and driven shafts or like members and an energy storing device in the 5 term of an inertia member or mass which alternat-ely absorbs energy from the driving member and gives suchenergy outeither to the driving or to the driven member or partly to each of these members. In previously proposed variable speed gears of the above type it, has been necessary to provident least one free wheel or like imidirectional driving device through which powerwas transmitted and difliculty has been experienced in providing a. free wheel device which would operate satisfactorily for a suflicient period under running conditions.

The object of the present invention is to provide variable speed gear or torque convol ter of the general type above referred to in which a unidirectional drive can be trans mitted without the use of free wheel or like devices.

A variable speed gear or torque converter 25 according to the present invention comprises in combination with. coaxial driving and driven shafts or like members a third member (hereinafter termed the mass member) or operatively connected to a mass and mounted to rotate coaxi'ailly with the driving and driven members,

shaft, hereinafter termed an intermediate shaft, freely carried by the driven member and rotatable about an axis out of line with the common axis of the drivin and driven members, and operative connections between the intermediate shaft and the driving member and between the intermediate shaft and the mass member such i. with the driven member stationary and speed the mass member will rotate always in the same sense as the driving member but at a varying speed, the torque produced on the driven member varying but beingalways in the same sense.

Thus the arrangement is such that with the driving member rotating at constant speed, the greater the difference between the speeds of the driving: and drivenmembers at any moment during either the acceleration or the deceleration of the mass member the greater the rate oi acceleration or deceleration of the mass member and thegreater the torque produced-on the mass member due to the inertia of the mass, there being noaccelerationor deceleration of the mass, and hence lo-torque on the mass member Whentheadriven member-rotates at the same speed and in the same sense assthe driving member. h-us during the normal driving condition in which the driven member is rotating in the same sense .-as,-but slower than the driving member, an increasing speed "of the driven member so that this speed approaches more nearly to the speed of the driving member will, during either the accelerating or decelerating phase of the mass member, produce a decrease in the-torque on the mass member by decreasing themagnitude ofthe accelerationor the deceleration. Similarly during the normal driidng conditiona decreasing speed of the driven member so as to increase the Vcli'tferen'ce in speed-between the driving and driven membersproduces during either the accelerating or decelerating phase otthe mass member an increase in the-magnitude of such acceleration or deceleration and hence of the torque on the mass member.

The form ofthe operative connections'betWeenth-e intermediate shaft andthe driving and mass members'to produce the desiredieffeet may vary but one at least of these operative connections must be of a type, hereinafter termed the varying ratio type, which will yield a constantly varying gear ratio between the members which it connects. Thus inone convenient arrangement the operative connection between thedriving member or the mass member and the intermediate shaft or each of these connections is in the form of gearing comprising an elliptical gear wheel mounted on one of the members to be connected with the axis of rotation of such member passing through one of the foci of the ellipse, such gear wheel meshing with a. similar elliptical gear wheel similarly mounted on the other member.

Alternatively, one or each of these operative connections may comprise a crank or the like on the intermediate shaft having a crank pin which engages but is capable of sliding radially relatively to an arm or the like on the driving or mass member. lVith such an operative connection the dimensions and ar rangement of the parts are such that with the driven member stationary and the driving member rotating the crank pin will slide freely in the slot in the arm and describe a circle eccentric to and enclosing the axis of the shaft carrying this arm.

In yet another arrangement one or each of these operative connections may comprise a link connected at its ends respectively to the intermediate shaft and the mass member or driving member by crank pins each of which lies at a greater distance from the axis of rotation of the member to which it is connected than the distance between the axes of the driving member and intermediate shaft. In a still further arrangement, one or each of these operative connections may comprise eccentrically mounted pulleys, sprockets or the like on the two members to be connected and a chain, belt or like flexible transmission member connecting the pulleys and sprockets. If desired, one of the forms of varying ratio operative connection indicated above may be employed to connect the intermediate shaft to the driving member and another of these operative conned tions be used to connect the intermediate shaft to the mass member.

In any case an operative connection of the type indicated above may be employed for connecting the intermediate shaft either to the driving or to the mass member, the other operative connection being either of a similar varying ratio type or of a type providing a constant gear ratio between the two elements connected.

The invention may be carried into practice in various ways but three alternative arrangements according to this invention are illustrated diagrammatically by way of example in the accompanying drawings, in which Figure 1 is a side elevation partly in section,

Figure 2 is an end elevation of the arrangement shown in Figure 1,

Figure 3 is a side elevation partly in section of an alternative arrangement,

Figure 4 is an end elevation of the arrangement shown in Figure 3,

Figure 5 is a side elevation partly in sec tion of a modified form of the arrangement shown in Figure 1, and I Figure 6 shows diagran'nnatically an alternative form of varying ratio operative connection which may be employed between the intermediate shaft and the di ng member or the mass member in a variable speed gear or torque converter according to the present invention.

In the construction illustrated in Figures 1 and 2, the apparatus comprises a driving shaft A rotatably mounted in a bearing support A and carrying rigidly secured to it an elliptical gear wheel B so arranged that the axis of the shaft A passes through one of the foci of the ellipse. Meshing with the elliptical gear wheel B is a similar elliptical gear wheel C rigidly connected to one end of a shaft C freely mounted to rotate in a support D. The support D is capable of rotating freely about the axis of the shaft A, and constitutes the driven member of the apparatus, to which end it is conveniently provided with gear teeth D ltigidly mounted on the other end of the shaft C is a circular gear Wheel C meshing with a similar circular gear wheel E rigidly connected to a shaft E which is freely mounted in a bearing support E and carries a mass member i l in the form of a flywheel. l the construction diagrammatically illustrated the driven member D is freely supported in a rotatable manner on the ends of the shafts A and E In the alter' "u' "on illustiri 10a c nn a dri 111g shaft rport- F and carrying a c 7 with a crank pin nk arm F provided l I l on" and ca a slot (ll in an arm {3: 1' .i to one on:

a shaft G wh able manne being mounter. in a l to be canable of coincident and constitut paratus.

Rigidl connected to th c shaft G is a second arm {l G and angularly d arm J is pro engaged by a crank p slot and carried on t K which is 'idly m The shaft 1-? is support K and car 'ics a in the form of a flywheel.

In the alternativeconstru' in Figure 5, the apparr lar to that shown struction shown in Fig .re driving shaft L which is me in a bearing support L has rigidly stituted by the periphery of such wheel,

a /eases to it an elliptical wheel I? meshing wi a similar ellr tical gear wheel T mounted on one of sin-intermediate sh which can rotate freely in a member member M being capable of rotating about the i 's of the driving sl and cor stituting the driven member of the device. Rigidly connected to the other end of the shaft L is a second elliptical meshing with simil elli N rigidly mounted on a r'ee to rotate in bearin camies inertia member ti'on the effective inertia of the in her can be var this end member comprises a sleeve r nected th shaft N and formed 1 Q and a second sir v O h lugs V" and capable of alidi 21201121 the shaft h Pivot-ed to s iugs fi is a lie I 3* the free end P connected by apivot to the 1' link 0 pivoted to one of the h" 0 being carr'ed posed between 1 e on spring G bf; mm st t c action of the i f the weights rom of the shaft and hence t in rtia member tio sleeve 0 sleev maticall shaft of the gear wheels L L L and N is me upon its shaft so that such shaft through one of the foci of the elh se conthe two gear wheels L and L be larly disposed'on the shaft one another that when th p i r c wheel if having the smallest di the arns oi the shalt L the gear wheel L the wheel L having the r. the axis of the shaft L is in engagement the gear wheel N shown.

Figure 6 shows an alternative form of operative connection which may be employed between the driving shaft orthe mass membar and the intermediate shaft of a variable speed gear or torque converter according to the present invention. In the arrangement diagrammatically shown, he driving shaft or the mass member P carries a crank arm P which is connected by a pivot P to one end of a link P The other end of the link P is connected by a pivot P* to the free end of a crank arm P carried by the intermediate shaft- P". The lengths of the crank arms P and P and the positions of the pivots P and P thereon are so determined that the distance of the pivot P from the axis of the driving shaft or mass member P is greater than the distance between the axes of the member P and the intermediateIsliaftP, while the distance of the pivot P from the axis of the intermediate shaft P is similarly greater than the distance of the axis of the member P from the axis of the intermediate shaft P Vith this arrangement it will be seen that with the axis of the intermediate shaft- P held stationary, i. c. with the driven member held stationary, and the member P rotated at constant speed, the speed of rotation of the intermediate shaft P about its own axis will vary continuously. Thus, for example, while the pivot P 'moves from position l to position 5,, only small rotation of the arm P and shaft P about its axis is offooted, whereas while the pivot P moves from position 5 to position 10 a very considerably greater rotational movement of the arm l 5 and shaft P takes place.

With constructions employing one or more operative connections of the type shown in Figure 6, the distance of the crank pins P and P respectively from the axes of the shafts P and P may vary. In all cases, however, as stated, the distance of the axis of each crank pin from the axis of the shaft carrying it must be greater than the distance between the axes of the two shafts P, P

The length of the l nk P may also vary but in all cases must lie between certain limits which may be defined as follows :Assuming the driven member and hence the axis of the intermediate shaft P to be stationary, then the. crank pins carried respectively by the intermediate shaft and the driving or mass member may be regarded as each describing a circle. Assuming now that a straight line be drawn passing through the centres of the two circles thus described, then this line may be regarded as a diameter of the larger circle which is intersected by the circumference of the smaller circle at two points, one of which lies nearer the centre of the larger circle than the other. The effective length of the link must lie between the lengths of the two pertions of this diameter of the larger circle which lie respectively on each side of the point nearer the center of the larger circle where the circumference of the smaller circle intersects such diameter. That is to say, in the construction shown in Figure 6 the l ngth. of the link must lie between the length a and the length 6 indicated on the drawing. 7

In some cases intermediate gearing or other operative connections carried by the driven member D may be interposed between the mechanism for transmitting movement from the driving shaft to the intermediate member or for transmitting motion from the intermediate member to the mass member and-such intermediate connections may in themselves provide for the continuously varying gear ratio necessary between the driving and mass members. In all cases, however, whether one or more intermediate shafts are provided, and whether one or more operative connections of the varying ratio type are employed, the arrangement must be such as set forth above that with the driving member rotating at a constant speed and the driven member stationary, the mass will be driven in the same sense as the driving member and at a constantly accelerating and decelerating speed, the rate of acceleration and deceleration of the mass and hence the torque on the mass member being the greater both during the accelerating and decelerating phase, the greater the diiference in the speeds of the driving and driven members, while when the driven member rotates at the same speed and in the same sense as the driving member there is no acceleration or deceleration of the mass member.

It will be seen. that in c, tions illustrated this tune Thus with any of the devices described, v the driving member rotating at a cone speed, if the driven member is rotating at t same speed and in the same sense there w be no acceleration or deceleration of the nu member and hence no torque on th s memb If, however, the driven member is rotating slower than the driving member or is rotating in the opposite sense, the mass meml'zer of the construc n is achieved.

will be subjected. to oscillating torque caused by the acceleration and deceleration of the mass, and this torque will produce i of alternating sign not only in the mar i her but also in the operative comiections between the intermediate shaft and the driving and mass members. Now, since the all ating torque in the mass member, vhethcr due to acceleration or deceleration of the mass at any moment or over any period can only be decreased or finally eliminated by accel ation of the driven member in the same sense and towards the same speed as the driving member, it follows that this torque must react on the driven meml er in a manner tr ding to cause it to rotate at the same speed and in the same sense as the driving men'facr since the reaction. on the driven men or must be in a sense tending to cause movement of the driven member in a direction in wh ch the reaction thereon will be reduced or elinn inated.

Thus long as the driven member is rotating slower than the driving memhe whenit is stationary, a torque will he exert thereon tending to rotate in the same s as the driving member, this torque l function of the difference in speed between the driving and driven nemberis. Thus, whereas in previous devices employing driving and driven member connected epicyclically in which variations in the relative speeds cause variations in the acceleration and deceleration of a mass, an accelerating rotation of the driven member would decrease the inertial torque only during either the accelerating or the decelerating phase and would increase it during the other phase so that the torque on the driven member was alternating and ratchets were required to yield a unidirectional drive, the apparatus ac cording to the present invention yields such a unidirectional drive without the necessity for ratchets or similar one way driving devices.

In some cases the characteristics of the gear may not be satisfactory where the effective inertia of the mass is constan Thus, means such as those illustrated in Figure 5 may be provided for varying the effective inertia of the mass.

Further, where means are provided as indicated above for varying the characteristics of the by varying the ellective inertia of the mass, this variation may either be effected manually or automatically, for example by a centrifugal or other governor operated in accordance with the speed of either the driving or the driven member. With such an arrangement the manner in which the characteristics of the gear are varied by the governor will depend upon the characteristics of such governor and a governor can he employed ha :ng the desired characterist'cs to suit the purpose for which the gear is to be employed.

Again, in some cases where mechanism is provided for varying the characteristics of he gear as indicated above, such mechanism may be ii'iterconnected with the throttle or other speed control mechanism of the internal combustion engine or other prime mover from which the driving shaft derives its power.

Such an arrangement might for example be used with. advantage on motor road ve-- hicles where it is dillicult or impossible, where the vehicle is intended to perate over a wide range of speeds or where normal speeds are considerably below maximum speec s, to obtain a good performance, good acceleration and engine econon'iy with a purely automatic gear according to this invention without means for varying the effective inertia of the mass, Thus in a motor road vehicle the throttle may be so interconnected. with mechanism for varying the eiit'ective inertia of the mass that this effective inertia is at a minimum when the throttle is in its idling position and increases rapidly to a maximum for the throttle position corresponding to normal speed, after which it decreases again as the throttle is moved to its fully open position.

It is to be understood that a ariable speeu gear or torque converter according to this invention is not limited to one intermediate shaft and a single mass member but if desired two or more intermediate shafts may be carried by the driven member, each of such shafts being operatively connected to the driving member and to mass member in the manner according to this invention, the mass members in such an arrangement being arranged coaxially a -d preferably concentrically.

Further tne operative connections between each intermediate shaft and the driving and mass members may vary and other constructional details be varied within wide limits while conforming to the conditions set out above, without departing from this invention.

W hat I claim as my invention and desire to secure by Letters Patent is 1. A torque converter including in combination coaxial driving and driven members, a third member mounted to rotate coaxially with the driving and driven members, a mass carried by the third member, an intermediate shaft rotatably carried by the driven member and lying parallel to but out of line with the driving and driven members, and operative connect-ions between the intermediate shaft and the driving member and between the intermediate shaft and the third member such that with the driven member stationary and the driving member rotating at a constant speed, the third member will rotate always in the same sense as the driving member but at a varying speed, whereas with the driving member rotating at a constant speed the greater the difference between the speeds of the driving and driven members during both the acceleration and deceleration of the third member, the greater the rate of acceleration or deceleration of the third member and the greater the torque produced on the third member due to the inertia of the mass, there being no acceleration or deceleration of the third member and hence no torque on the mass when the driven member rotates at the same speed and in the same sense as the driving member.

2. A torque converter including in combination coaxial driving and driven members, a third member mounted to rotate coa-Xially with the driving and driven members, a mass, an operative connection between the third member and the mass, an intermediate shaft rotatably carried by the driven member and lying out of line with the driving and driven members, and operative connections between the intermediate shaft and the driving member and between the intermediate shaft and the mass member at least one of which is of a nature providing a continually varying gear ratio as between the two members it connects.

3. A torque converter including in combination coaxial driving and driven members, a third member mounted to rotate coaxially with the driving and driven members, a mass, an operative connection between the third member and the mass, an intermediate shaft rotatably carried by the driven member and lying parallel to but out ofline with the driving and driven members, and operative connections between'the intermediate shaft and the driving member and between the intermediate shaft and the mass. member, at least with the driving and driven members, a mass mounted on the third member, an intermediate shaft rotatably carried by the driven member and lying parallel to but out of line with the driving and driven members, and operative connections between the intermediate shaft and the driving member and between the intermediate shaft and the third member, at least one of which is of a nature providing a continually varying gear ratio as between the two members it connects.

5. A torque converter including in combination coaxial driving and driven members, a third 1 ember mounted. to rotate coaxially with the driving and driven members, a mass, an operative connection between the. third member and the mass, an intermediate shaft rotatably carried by the driven member and lying parallel to but out of line with the driving and driven members, and operative connections between the intermediate shaft and the driving member and between the in termediate shaft and the third member, at least one of which comprises two intermeshing elliptical gear wheels similarly eccentrically mounted on the two members to be connected.

6. A torque converter including in combination coaxial driving and driven members, a third member mounted to rotate coaxially with the driving and driven members, a mass, an operative connection between the third member and the mass. an intermediate shaft rotatably carried by the driven member and lying parallel to but out of line with the driving and driven members, and operative con nections between the intermediate shaft and the driving member and between the inter mediate shaft and the third member, at least one of which comprises a link, pivots connecting the ends of the link respectively to the intermediate shaft and one of the said members, each of said pivots lying at a greater distance from the axis of rotation of the member carrying it than the distance between the axes of the driving member and the intermediate shaft.

7. A torque converter including in combination coaxial driving and driven members, a third member mounted to rotate coaxially with the driving and driven members. a mass, an operative connection between the third member and the mass, an intermediate shaft mtatahly carried by the driven 111e111he1' and lying parallel in but ent of line with the (lri'v 1 i11 and (111i \011 111en'1be1s, and operative cennect-iens between the inlerniediate shaft and the driving member and between the internuxliafe shaft and the third member, at least one of which comprises an :11111 011 one of the said 111en1be1's having a longitudinal slot therein, a crank en the llllellnfitiiflllil shaft, and a crank pin on the crank which engages but is capable of sliding in the $105 in the arm.

In testimony whereof I have signed my name to this specification.

CHRISTOPHER ST. JOHN SPRIGG. 

